The Indiana Jones pants are made of wool. They have these hard-to find flaped backpockets.
They where originally cutommade for the movie, but You can find a great alternative at the great american postorder-compagny, L.L. Bean. If this link doen´t work seach for "Dress Chinos - natural fit".
The most acurate colour is "Taupe". They are in a great quality and the price are quite reasonable too. But if You are living in Europe, mind the custom!!! Only thing that is a "turndown" is that they all got a fixed crease - so it will take a lot of wear to make them look really good (Indy-like).
From "Temple of Doom" or from this promotionspicture (Raiders)
However these screenshoots shows the pants as more browinsh. Light and angels has a great impact on color (ex. my fedora looks rather grey in the "Fedora-section", but it is actually dark brown).
From Raiders (left) and LC (right) - no doubt that these are same style of pants.
My L. L. Bean - pants
This is how they are displayed at L.L. Bean: There is, however another alternative that is even more autentic:
You can read more about them HERE , but they are very close to the originals. However Wested has just opened for sale of the Indy-pants too. More info comming up!